Photosensitive copper glass and method of making it



Patented July 18, 1950 PHUTOSENSITIVE COPPER,GLASS AND METHOD OF MAKING IT Stanley Donald Stookey, Corning, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corporation of New York No Drawing. Application December 8, 1943, Serial No. 513,444

4 Claims. (Cl. 49-92) This invention relates to photosensitive glasses, that is, glasses in which exposure to short wave radiations such as ultraviolet brings about a change in the glass as :a result of which irradiated areas are capable of heat-developed coloration whileL-non-irradiated areas remain substantially unchanged on heating. In .Patent 2,326,012 which was issued August 3, 1943, to Robert H. Dalton and assigned to the assignee of the present application, there are disclosed reduced coppercontaining glasses which are photosensitive.

According to the patent when a glass containing C1120 and melted reducingly, is irradiated with short waves such as ultraviolet, X-rays, radioactive radiations, etc., the heat-developed coloration produced by warming in will thereafter occur at a lower temperature and/or in a shorter time than it otherwise would. If the composition of the glass is such that it would not readily warm in, that is, if the Cu2O content is between about 0.05% and 1% depending, as pointed out in the Dalton patent, on the thinness of the glass article being treated, such irradiation will cause the irradiated parts to develop color on heating while unexposed parts will remain uncolored. By suitably masking selected portions of the glass or protecting them against irradiation as by interposing a photographic negative between the glass and the source of the effective radiations, images and designs can be formed in the glass. The presence oftin oxide in the glass is desirable for the heat development of a red coloration in the irradiated parts.

The primary object of this invention is to increase the photosensitivity of the above described glasses.

Another object is to improve the contrast and detail of images and designsformed in copper containing photosensitive glasses by selective irradiation.

I have discovered that the above and other objects may be accomplished by including a small amount of cerium oxide in the prior copper containing photosensitive glasses. Amounts as small as about 0.05% CeOz on the oxide basis introduced into the batch are sufficient to produce such efiects. Larger amounts cause absorption of the effective radiationsand decrease or inhibit photosensitivity.

I have also found that substantial amounts of ultraviolet absorbing substances such as oxides of iron, lead, uranium, vanadium, etc., when present in the glass, also inhibit photosensitivity, or at least prevent penetration of the eflective Sand 330 330 330 Sodium carbonate. Hydrated alumina. Calcium carbonate.

Copper oxide Stannic oxide Cerium dioxide uear Ammonium chloride 8 t0 9 As a reducing agent, sugar is used in batches 1 and 2 and ammonium chloride is used in batch 3. Ammonium chloride acts as a very mild reducing agent in copper containing photosensitive glasses and is useful because it permits a very accurate reduction of such glasses to the optimum photosensitivity. The exact amount of reducing agent required in all cases cannot be stated because it will depend upon the size and type of melting container and other factors. However, the proper amount of reducing agent for any given conditions can be readily determined by trial, and the above examples are suitable for melting in closed pots of 800 pounds capacity.

It is to be understood that photosensitivity, as used herein, excludes the so-called solarization effect which has long been recognized as common to glasses containing manganese, iron or other polyvalent metals. The discoloration of glass caused by solarization is not permanent but is destroyed by heating the glass. The photosensitivity of glasses of the present invention is distinguished from solarization in that the coloration of the photosensitive glass is developed by heating at temperatures below the softening point of the glass and cannot be destroyed by such heating. The term reduced silicate glass, as used in the claims, means a glass prepared by fusion of raw glassmaking materials under reducing conditions, containing on the oxide basis a major proportion of silica and a minor proportion of an alkali metal oxide such as sodium oxide, containing minor proportions of other conventional glass-forming oxides such as calcium oxide and alumina, but being free of constituents which inhibit photosensitivity including compounds of iron, lead, uranium, and vanadium.

1 claim:' cle uniformly for a time and at a temperature 1. A photosensitive glass consisting essentially suflicient to develop color in the exposed area. of a reduced silicate glass containing on the oxide STANLEY DONALD STOOKEY. basis by weight 0.05% to 1% of copper computed as CuzO and CeOz in an amount up to 0.05%. 5 REFERENCES CITED An article comppising a body made of a The following references are of record in the photosensitive glass consisting essentially of a file of t v patent: reduced silicate glass containing 0n the oxide basis by weight 0.05% to 1% of copper computed. UNITED STATES PATENTS as C1120 and CeOz in an amount up to 0.05%, 10 Number Name Date selected portions of said body being colored by 270,991 Sindell Jan. 23, 1883 the copper to form within its mass a heat-stable 332,294 Shirley Dec. 15, 1885 image exhibiting photographic detail. 337,170 Libbey Mar. 2, 1886 3. An article comprising a body of irradiated, 343,823 Libbey June 15, 1886 substantially colorless photosensitive glass con- 15 366,364 Atterbury July 12, 1887 sisting essentially of a reduced silicate glass con- 851,317 Reimnann Apr. 23, 1907 taining on the oxide basis by weight 0.05% to 1% 1,169,571 Rosenthal Jan. 25, 1916 of copper computed as C1120 and CeOz in an 1,475,573 Drescher Nov. 27, 1923 amount up to 0.05%, said body containing within 1,482,389 DAdrian Feb. 5, 1924 its mass a predetermined latent photographic 20 1,771,435 Gelstharp July 29, 1930 image capable of being developed, by uniform 1,899,230 Crowell Feb. 28, 1933 heating of the entire glass body, into a visible, 2,049,765 Fischer Aug. 4, 1936 colored image exhibiting photographic detail. 2,068,801 Hood Jan. 26, 1937 4. The method of making a glass article which 2,241,950 Huniger et a1 May 13, 1941 comprises forming an article of a substantially 2 2,306,626 Hun iger et a1. Dec. 29, 1942 colorless photosensitive glass consisting essen- 2,326,012 Dalton Aug. 3, 1943 tially of a reduced silicate glass containing on 2,422,472 Dalton June 17, 1947 the oxide basis by weight 0.05% to 1% of copper computed as CuzO and C602 in an amount up OTHER REFERENCES l to 0.05%, exposing an area of the article to short- 0 Gregory, Uses and Applications of Chemical wave radiations and thereafter heating the arti- Related Materials, vol. II, page 19. 

2. AN ARTICLE COMPRISING A BODY MADE OF A PHOTOSENSITIVE GLASS CONSISTING ESSENTIALLY OF A REDUCED SILICATE GLASS CONTAINING ON THE OXIDE BASIS BY WEIGHT 0.05% TO 1% OF COPPER COMPUTED AS CU2O AND CEO2 IN AN AMOUNT UP TO 0.05%, SELECTED PORTIONS OF SAID BODY BEING COLORED BY THE COPPER TO FORM WITHIN ITS MASS A HEAT-STABLE IMAGE EXHIBITING PHOTOGRAPHIC DETAIL. 